The present invention relates to a defects inspection apparatus of a magnetic disk substrate or a semiconductor wafer or the like, in particular, relates to, in a method for mutually comparing or checking a plurality sets of a detected data obtained by repeated inspection of the same substrate, or a plurality sets of an inspected data obtained by inspection of the same substrate using an inspection apparatus before and after process treatment, a defect inspection method, wherein a state of defects coincidence or non-coincidence is output or displayed; and an apparatus therefor.
As a magnetic recording medium used in a hard disk apparatus, a disk substrate vapor deposited with a magnetic substance is used. Data is magnetically recorded and reproduced on and from this disk substrate, by magnetization with a magnetic head. Recently, with improvement of recording density in a hard disk apparatus, spacing (hereafter referred to as a flying height) between a head for recording and writing (hereafter referred to as a head) and a disk substrate has extremely been narrowed as small as several tens nm to several nm; therefore, presence of depression/protrusion defects larger than the flying height, on this disk substrate, makes the disk substrate and the head contacted, and causes failure of a hard disk apparatus. Therefore, in a state before vapor deposition of a magnetic substance, it is important to inspect presence or absence of the above defect, and not to flow a defect product to the downstream steps.
These defects include crystal defects embedded inside a disk substrate material, residue of abrasive grains, or fine scratch (scratch or the like) generating in polishing for improvement of flatness of a disk substrate, or foreign matters adhering in cleaning or drying or the like.
Foreign matters adhered on a surface can be removed or prevented by re-cleaning, cleaning-up of surrounding atmosphere or the like. However, crystal defects or scratch or the like cannot be corrected, resulting in handling as a defect product; therefore, to ensure high yield and high reliability of a hard disk apparatus, early stage removal of a disk substrate having such defects is important. In addition, also after vapor deposition of a magnetic substance, the above defects are considered to generate by certain causes, therefore surface state inspection is also necessary.
In the above inspection apparatus of a surface state, it is naturally an important item to remove defect goods of a disk substrate inspected, but also to monitor an apparatus state so as to maintain good condition, even in an apparatus to produce a disk substrate, to improve yield. It is also an important item to analyze, based on the above detection result of an inspection apparatus, whether or not such defects are derived from production apparatus failure, or foreign matters adhered in conveying between production apparatuses. Analysis based on defects data output from an inspection apparatus requires understanding of the place where the defects generated, along with positions, shapes and kinds of the defects.
In a conventional surface inspecting apparatus, as described in JP-A-2004-170092, there is a system for displaying a defect map based on defects kinds and sizes, from characteristics of defects detected. Position information (coordinates) of defects obtained by detection using an inspection apparatus, is position information in a rotation direction and in a radius direction. Because a hard disk apparatus rotates a circular plate-like disk substrate in high speed, in a state of maintaining only a small gap with a magnetic head, uniformity of a surface shape of the disk substrate is required. Therefore, a cut edge such as a notch cannot be provided, like a wafer used in production of a semiconductor device. In addition, because whole surface of a disk substrate is used for magnetic recording, pattern recording for a servo drive or the like, marking at the outer circumference or inner circumference is usually not allowed. Therefore, in general, coordinate standard cannot be set in a disk substrate. Therefore, in an inspection apparatus of a disk substrate, an inspection start position, in a fixed state of a disk substrate at an inspection apparatus, is used as the standard, and data of coordinates in a rotation direction and in a radius direction, namely position of a polar coordinate system, is prepared based on this standard.
Therefore, in a state that a disk substrate is mounted on an inspection apparatus, the coordinates are controlled, which makes finding out objective defects easy. However, once a disk substrate is taken out from the inspection apparatus, the coordinates are reset, and thus, even when the same disk substrate is re-inspected, coincidence of coordinates with the previous inspection results is difficult; that requires comparison using defects map output by each inspection, on difference in kinds, coordinates and number of defects by each of the inspections. Therefore, in the case of a plurality of inspections, and coordinate origins of defects maps output by each of the inspections do not coincide, a problem is raised that determination on whether or not the defects are the same defect, or foreign matters adhered this time is ambiguous, from information on the defect maps outputs.
In addition, also in carrying out surface inspections before and after a production step, insufficient inspected data makes discrimination difficult whether or not defects are newly generated in the production step, or generated in previous steps from the production step thereof, resulting in correct determination impossible on a state of a production apparatus. Furthermore, in the case of defects matching in an apparatus other than surface inspection apparatus, which is capable of similarly outputting defects in a rotation direction and in a radius direction (for example, an inspection apparatus of magnetic characteristics, described in JP-A-2000-57501), coordinate coincidence is difficult; therefore, even by analysis back to the previous steps, when critical defects generates, sufficient analysis may be inhibited because coordinates provide no coincidence, or insufficient matching.
As described above, a conventional inspection apparatus gave no consideration of use of inspected data for analysis, which raised a problem of inability of mutual determination by inspected data.
Because there was no consideration of inspected data of detected results for mutual utilization, in an inspection apparatus for inspecting a circular sample such as a disk substrate, which cannot prepare position standard, inspected data could not effectively be utilized.